I agree with you totally, SNGX1275.
The point of the one province in China, is that many of the power supplies made there are often made in the same plant. they are nearly all the same... but when one puts more wattage without changing the engineering, to meet a marketing brochure, then you have probably gained nothing.
The part the differentiates the power supplies is the UL code on the label Some brand names and models have identical UL code is the same, meaning it has been tested by United Laboratories, and accepted for US distribution.
As to backing it up, a Gurgle search will provde you with plenty. There have been some super articles by PCPower and Cooling in CPU magazine, among others.
In general, wattage is not very important once it is above 550 watts, as long as the distribution along the 12V rail(s) is correct. Amperage that is steady is critical. A great cooling fan. Quality transisters, resistors, circuit boards... and the ability to maintain steady output underload.
Except for a few of the PC Power and Cooling power supplies, you don't know what you have, if anything, with a high wattage unit.
Look at the intensive reviews at
www.tomshardware.com,
www.anandtech.com, or do a Gurgle search for power supply reviews... for those that are tested under load, and tested for heat and circuit fidelity.
As mentioned above, if it has reserve power after supplying the needs of the video graphics card, the engineering is probably good regardless of the wattage on the label.
The power supply postings on this forum that list acceptable models is pretty good, although they downrate some pretty good power supplies that I have never seen fail.
Properly referenced, the power supply in most of the computers you will work on are referenced as "Constand voltage switching power supply," and this is supposed to mean that the power supply puts out the same voltate to all the interal components, no matter the voltage of the AC current that runs it, or the capacity of that power supply. Switching power supply refers to the techniques used in regulation to assure that the power supply perform these tasks in a small, standard sized unit, at a low price.
But it has become a place to make a lot of profit. It wasn't that long ago that a good power supply cost $35 and a great one cost $65. Most of the rest is money in the bank, not performance for the computer. Only the improved designs of video graphics components changed that mix.
Most failures were to lousy components in the power supply. Some were sold in volume for $5.00 each to the likes of such manufacturers as Compaq and the rest.
There are basically needs for +3.3 Volts, +5 volts, and +12 volt rails, which were techically set aside to be independent within the power supply. But the cheapos started finding ways to share circuitry, making them less independent than they should be, and thus a lot less reliable.
Finally, the power supply must ensure that the system doesn't run unless and until the voltages supplied are able to operate the system properly. The power supply should actually prevent startup if there is not sufficient power detected by the motherboard. This Power Good signal must always be present in order for the motherboard to run.
When the power supply is well built with quality components that do not burn out like a light bulb, then good power results. When the power dips or rises, the signal that there is good power is gone, and the computer resets.
In gamer systems, there are many devices that detect that power output is correct. Video cards won't run without it. Memory will not. So that output of the power supply must be adequate for all demands, regardless of what demands are made on it. Poor components and circuits too far out of range foul up this system. Some computers quit. Some burn out key componets before they have time to quit.
The better the circutry, the better the power supply meets the demands on all these rails. Some are not engineered well enough to do so. Some do not have electrical components adeequate to the task. Some burn out.
